Tool head attachment mechanism

ABSTRACT

A tool head attachment mechanism located within a tool body retains a replaceable tool head in an opening of the tool body. The mechanism includes a retaining ring including a wall having a number of apertures therethrough. A locking ring is rotatable with respect to the retaining ring. Ball bearings equivalent in number to the number of apertures are retained between the locking ring and the retaining ring. The ball bearings are sufficiently large to extend partially, but not completely through the apertures. The locking ring includes ramps equivalent in number to the number of ball bearings and against each of which a respective one of the ball bearings rolls when the locking ring is rotated with respect to the retaining ring to thereby move the ball bearings radially to partially project through said apertures and retain the tool head to the tool body

BACKGROUND OF THE INVENTION

[0001] The present invention relates to a tool head attachment mechanism. More particularly, although not exclusively, the invention relates to a mechanism formed within a tool body and by which a tool head such as a drill chuck mechanism, can be attached so as to receive output torque from an electric motor housed within the tool body.

[0002] In the art of electric power tools such as electric drills and angle grinders for example, a recent development has been the invention of replaceable tool heads removably attachable to a common tool body. The common tool body houses an electric motor from which there extends an output sprocket. The tool body usually also has a handle and a trigger to activate the motor. An electric power cord can extend from the base of the handle, or alternatively, there might be provision for the attachment of a rechargeable battery pack.

[0003] At the front end of the housing, there is an opening within which the spindle is located. Adjacent to the opening is a pair of radially opposed clamp levers such as those depicted at 4 in FIG. 1. These clamp levers are attached to a disk 1 located between a pair of washers 3 and retained within the tool body behind a retaining washer 2. The disk 1 has a pair of radially opposed tabs to which the clamp levers 4 are attached. Once the tool head is attached to the tool body, the clamp levers 4 are rotated about a longitudinal axis of the tool body to thereby rotate the disk 1 whereupon inwardly projecting bayonet plates formed integrally with the disk move behind radially extending parts of a tool head spigot. Although this results in retaining the tool head spigot within the opening of the tool body, the arrangement is complex and prone to wear as there is sliding contact between adjoining parts.

OBJECTS OF THE INVENTION

[0004] It is an object of the present invention to overcome or substantially ameliorate at least one of the above disadvantage and/or more generally to provide improved tool head attachment mechanism for retaining a tool head to a tool body.

DISCLOSURE OF THE INVENTION

[0005] There is disclosed herein a tool head attachment mechanism located within a tool body and adapted to retain a replaceable tool head in an opening of the tool body, the mechanism comprising:

[0006] a retaining ring including a wall having an aperture therethrough,

[0007] a locking ring rotatable with respect to the retaining ring,

[0008] a ball bearing retained between the locking ring and the retaining ring, and being sized to extend partially, but not completely through said aperture, and wherein:

[0009] the locking ring includes a ramp against which the ball bearing rolls when the locking ring is rotated with respect to the retaining ring to thereby move the ball bearing radially to partially project through said aperture.

[0010] Preferably the mechanism includes a plurality of said apertures through said retaining ring wall,

[0011] a plurality of said ball bearings equivalent in number to said plurality of apertures, each ball bearing being retained between the locking ring and the retaining ring, and each being sized to extend partially, but not completely through said apertures, and wherein:

[0012] the locking ring includes a plurality of said ramps equivalent in number to the number of ball bearings and against each of which a respective one of the ball bearings rolls when the locking ring is rotated with respect to the retaining ring to thereby move all of the ball bearings radially to partially project through said apertures.

[0013] Preferably the locking ring has a lever extending radially therefrom by which the locking ring can be rotated.

[0014] Preferably the retaining ring has a pair of radially opposed tabs by which the retaining ring is fixed with respect to the tool body.

[0015] Preferably one end of each ramp has a deep recess within which one of said ball bearings can reside, and the other end of each ramp has a shallow recess to support said one ball bearing when it is partially projecting through one of said apertures.

[0016] There is further disclosed here in a tool body having an opening to receive a spigot member of a replaceable tool head, the tool body having a tool head attachment mechanism located in said opening, the mechanism comprising:

[0017] a retaining ring including a wall having an aperture therethrough,

[0018] a locking ring rotatable with respect to the retaining ring,

[0019] a ball bearing retained between the locking ring and the retaining ring, and being sized to extend partially, but not completely through said aperture, and wherein:

[0020] the locking ring includes a ramp against which the ball bearing rolls when the locking ring is rotated with respect to the retaining ring to thereby move the ball bearing radially to partially project through said aperture.

[0021] Preferably the tool body includes a plurality of said apertures through said retaining ring wall,

[0022] a plurality of said ball bearings equivalent in number to said plurality of apertures, each ball bearing being retained between the locking ring and the retaining ring and each being sized to extend partially, but not completely through said apertures, and wherein:

[0023] the locking ring includes a plurality of said ramps equivalent in number to the number of ball bearings and against each of which a respective one of the ball bearings rolls when the locking ring is rotated with respect to the retaining ring to thereby move all of the ball bearings radially to partially project through said apertures.

[0024] There is further disclosed here in a tool body having a replaceable tool head attached thereto, the tool head comprising an attachment spigot member having a recess formed therein and a tool head attachment mechanism located within the tool body and adapted to retain the tool head in an opening of the tool body, the attachment mechanism comprising:

[0025] a retaining ring including a wall having an aperture therethrough,

[0026] a locking ring rotatable with respect to the retaining ring,

[0027] a ball bearing retained between the locking ring and the retaining ring, and being sized to extend partially, but not completely through said aperture, and wherein:

[0028] the locking ring includes a ramp against which the ball bearing rolls when the locking ring is rotated with respect to the retaining ring to thereby move the ball bearing radially to partially project through said aperture and engage with said recess.

[0029] Preferably the tool body comprises a plurality of said recesses formed in an array about said spigot, and the wall of said retaining ring having a plurality of said apertures therethrough, a plurality of said ball bearings equivalent in number two said apertures and retained between the locking ring and the retaining ring and wherein the locking ring includes a plurality of said ramps against which the respective ball bearings roll when the locking ring is rotated with respect to the retaining ring to thereby move all of the ball bearing radially to partially project through said apertures and engage with respective ones of said recesses.

[0030] There is further disclosed here in a set including a tool body and a plurality of replaceable tool heads for individual attachment to the tool body, the tool heads each comprising an attachment spigot member having a recess formed therein, and a tool head attachment mechanism located within the tool body and adapted to retain each tool head in an opening of the tool body, the attachment mechanism comprising:

[0031] a retaining ring including a wall having an aperture therethrough,

[0032] a locking ring rotatable with respect to the retaining ring,

[0033] a ball bearing retained between the locking ring and the retaining ring, and being sufficiently large in diameter to extend partially, but not completely through said aperture, and wherein:

[0034] the locking ring includes a ramp against which the ball bearing rolls when the locking ring is rotated with respect to the retaining ring to thereby move the ball bearing radially to partially project through said aperture.

[0035] Preferably the attachment mechanism includes a plurality of said apertures through said retaining ring wall,

[0036] a plurality of said ball bearings equivalent in number to said plurality of apertures, each ball bearing being retained between the locking ring and the retaining ring, and each being sized to extend partially, but not completely through said apertures, and wherein:

[0037] the locking ring includes a plurality of said ramps equivalent in number to the number of ball bearings and against each of which a respective one of the ball bearings rolls when the locking ring is rotated with respect to the retaining ring to thereby move all of the ball bearings radially to partially project through respective ones of said apertures.

BRIEF DESCRIPTION OF THE DRAWINGS

[0038] A preferred form of the present invention will now be described by way of example with reference to the accompanying drawings, wherein:

[0039]FIG. 1 is a schematic parts-exploded perspective illustration of a prior art tool head attaching mechanism,

[0040]FIG. 2 is a schematic parts-exploded perspective illustration of a tool head attaching mechanism of the preferred embodiment,

[0041]FIG. 3 is a schematic front elevational view of the mechanism of FIG. 2,

[0042]FIG. 4 is a schematic cross-sectional side elevational view of the mechanism taken at F-F in FIG. 3,

[0043]FIG. 5 years a schematic side elevation of a tool body half,

[0044]FIG. 6 is a schematic parts partially-exploded perspective illustration of a tool body, a tool head and a rechargeable battery pack,

[0045]FIG. 7 is a schematic perspective illustration of the tool body, cool head and rechargeable battery pack of FIG. 6,

[0046]FIG. 8 is a schematic partial elevational view of a tool head spigot,

[0047]FIG. 9 is another schematic partial elevational view of the tool head spigot of FIG. 8,

[0048]FIG. 10 is a schematic front elevational view of the spigot of FIGS. 8 and 9,

[0049]FIG. 11 is a schematic cross-sectional front elevational view of the attachment mechanism surrounding the spigot in a locked configuration,

[0050]FIG. 12 is a schematic cross-sectional front elevational view of the attachment mechanism surrounding the spigot in an unlocked configuration, and

[0051]FIG. 12 is a schematic perspective illustration of a tool body and a number of alternative tool head attachments.

DESCRIPTION OF THE PREFERRED EMBODIMENT

[0052] In FIGS. 2 and 3 of the accompanying drawings there is schematically depicted a tool head retaining mechanism comprising a locking ring 7 typically fabricated from moulded plastic material. The locking ring includes a pair of diametrically opposed levers 10, which would project outwardly from the tool body 26 (shown in FIG. 6 for example).

[0053] The locking ring 7 includes an integrally formed back plate 14.

[0054] A retaining ring 6 having a pair of diametrically opposed tabs 9 fits in front of the locking ring 7 at the back portion of an opening 30 in the tool body 26. Opening 30 receives spigot 21 of a tool head such as a drill head 11. Spigot 21, unlike some prior art drill head spigots years of generally cylindrical shape of constant diameter.

[0055] The retaining ring includes a wall 13 having 6 apertures 27 spaced evenly thereabout. The apertures 27 are large enough to enable the ball bearings 8 to partially project therethrough, yet not the whole way therethrough.

[0056] As better shown in FIG. 11, the locking ring 7 includes six ramps 18, each having a deep recess 16 at one end and a shallow recess 17 at the other. When the locking ring is turned in the direction indicated by arrow B in FIG. 11 by pushing on either one or both of the levers 10, the ball bearings 8 roll against the respective ramp surface toward the shallow recess 17. As the retaining ring 6 is held against rotation within the tool body 26 by virtue of tabs 9, the ball bearings move partially through the apertures 27.

[0057] If the levers 10 are moved in the opposite direction as indicated by arrow C in FIG. 12, the ball bearings 8 are allowed to recede back into the deep recesses 16 as shown. In other words, whereas the radial movement of the ball bearings is an inward movement during the locking action, the radial movement is outward during the unlocking action.

[0058] The spigot 21 includes a number of recesses. There might be a continuous annular recess, a pair of recesses, or a small recess 23 corresponding to each of the ball bearings 8. when the ball bearings 8 take on the positions as depicted in FIG. 11, the protruding parts thereof are received within the respective recess 23 to thereby axially retain the spigot 21. The tool head is therefore fixed to the tool body for use.

[0059] It should of course be noted that there is an electric motor 13 within the tool by the 26 having an output shaft on which there is a drive sprocket 31. The spigot 21 includes an internal receiving sprocket within which sprocket 31 is received to transmit torque to the tool head.

[0060] In order to align the spigot 21 with the opening 30, there is provided a slot 32 at the base of the opening 30 within which an alignment tab 24 must be received into insert the spigot 21 into the opening 30. This will ensure that if there is a plurality of discrete apertures for each ball bearing, then those apertures will align with the bearings for engagement. The alignment tab 24 also ensures that the spigot cannot rotate freely within the opening 30 upon transmission of torque from the motor to the tool head.

[0061] It should be appreciated that modifications and alterations obvious to those skilled in the art are not to be considered as beyond the scope of the present invention. For example, there might be only three ball bearings and associated apertures and ramps or any other number greater or smaller than 6 as illustrated. 

1. A tool head attachment mechanism located within a tool body and adapted to retain a replaceable tool head in an opening of the tool body, the mechanism comprising: a retaining ring including a wall having an aperture therethrough, a locking ring rotatable with respect to the retaining ring, a ball bearing retained between the locking ring and the retaining ring, and being sized to extend partially, but not completely through said aperture, and wherein: the locking ring includes a ramp against which the ball bearing rolls when the locking ring is rotated with respect to the retaining ring to thereby move the ball bearing radially to partially project through said aperture.
 2. The mechanism of claim 1, including a plurality of said apertures through said retaining ring wall, a plurality of said ball bearings equivalent in number to said plurality of apertures, each ball bearing being retained between the locking ring and the retaining ring, and each being sized to extend partially, but not completely through said apertures, and wherein: the locking ring includes a plurality of said ramps equivalent in number to the number of ball bearings and against each of which a respective one of the ball bearings rolls when the locking ring is rotated with respect to the retaining ring to thereby move all of the ball bearings radially to partially project through said apertures.
 3. The mechanism of claim 2, wherein the locking ring has a lever extending radially therefrom by which the locking ring can be rotated.
 4. The mechanism of claim 1, wherein the retaining ring has a pair of radially opposed tabs by which the retaining ring is fixed with respect to the tool body.
 5. The mechanism of claim 2, wherein one end of each ramp has a deep recess within which one of said ball bearings can reside, and the other end of each ramp has a shallow recess to support said one ball bearing when it is partially projecting through one of said apertures.
 6. A tool body having an opening to receive a spigot member of a replaceable tool head, the tool body having a tool head attachment mechanism located in said opening, the mechanism comprising: a retaining ring including a wall having an aperture therethrough, a locking ring rotatable with respect to the retaining ring, a ball bearing retained between the looking ring and the retaining ring, and being sized to extend partially, but not completely through said aperture, and wherein: the locking ring includes a ramp against which the ball bearing rolls when the locking ring is rotated with respect to the retaining ring to thereby move the ball bearing radially to partially project through said aperture.
 7. The tool body of claim 6, including a plurality of said apertures through said retaining ring wall, a plurality of said ball bearings equivalent in number to said plurality of apertures, each ball bearing being retained between the locking ring and the retaining ring and each being sized to extend partially, but not completely through said apertures, and wherein; the locking ring includes a plurality of said ramps equivalent in number to the number of ball bearings and against each of which a respective one of the ball bearings rolls when the locking ring is rotated with respect to the retaining ring to thereby move all of the ball bearings radially to partially project through said apertures.
 8. A tool body having a replaceable tool head attached thereto, the tool head comprising an attachment spigot member having a recess formed therein and a tool head attachment mechanism located within the tool body and adapted to retain the tool head in an opening of the tool body, the attachment mechanism comprising: a retaining ring including a wall having an aperture therethrough, a locking ring rotatable with respect to the retaining ring, a ball bearing retained between the locking ring and the retaining ring, and being sized to extend partially, but not completely through said aperture, and wherein: the locking ring includes a ramp against which the ball bearing rolls when the locking ring is rotated with respect to the retaining ring to thereby move the ball bearing radially to partially project through said aperture and engage with said recess.
 9. The tool body of claim 8 comprising a plurality of said recesses formed in an array about said spigot, and the wall of said retaining ring having a plurality of said apertures therethrough, a plurality of said ball bearings equivalent in number two said apertures and retained between the locking ring and the retaining ring and wherein the locking ring includes a plurality of said ramps against which the respective ball bearings roll when the locking ring is rotated with respect to the retaining ring to thereby more all of the ball bearing radially to partially project through said apertures and engage with respective ones of said recesses.
 10. A set including a tool body and a plurality of replaceable tool heads for individual attachment to the tool body, the tool heads each comprising an attachment spigot member having a recess formed therein, and a tool head attachment mechanism located within the tool body and adapted to retain each tool head in an opening of the tool body, the attachment mechanism comprising: a retaining ring including a wall having an aperture therethrough, a locking ring rotatable with respect to the retaining ring, a ball bearing retained between the locking ring and the retaining ring, and being sufficiently large in diameter to extend partially, but not completely through said aperture, and wherein: the locking ring includes a ramp against which the ball bearing rolls when the locking ring is rotated with respect to the retaining ring to thereby move the ball bearing radially to partially project through said aperture.
 11. The set of claim 10, including a plurality of said apertures through said retaining ring wall, a plurality of said ball bearings equivalent in number to said plurality of apertures, each ball bearing being retained between the locking ring and the retaining ring, and each being sized to extend partially, but not completely through said apertures, and wherein: the locking ring includes a plurality of said ramps equivalent in number to the number of ball bearings and against each of which a respective one of the ball bearings rolls when the locking ring is rotated with respect to the retaining ring to thereby move all of the ball bearings radially to partially project through respective ones of said apertures. 